1. Field of the Invention
The present invention relates to a pulse combustor for repeating pulsative explosion and combustion, and more specifically to a silencer device used in such a pulse combustor.
2. Description of the Related Art
Conventional pulse combustors for continuing combustion of an air/fuel mixture by pulsative explosion thereof generally include a silencer device such as a muffler for reducing a relatively large noise due to the pulsative explosion and combustion. FIG. 4 schematically illustrates such a conventional pulse combustor.
The pulse combustor of FIG. 4 primarily consists of a combustion-exhaust system, an air supply system, and a fuel gas supply system. The combustion-exhaust system includes a combustion chamber 1 for pulse combustion, a tail pipe 2 constituting an exhaust conduit of hot combustion byproducts discharged from the combustion chamber 1, a decoupler 3 connected to the tail pipe 2, and an exhaust muffler 4 connected to the decoupler 3. The air supply system for supplying air to the combustion chamber 1 includes a fan 5 for feeding the air for combustion, and an air chamber 6 coupled with and connected to the combustion chamber 1 for receiving the air fed by the fan 5. The fuel gas supply system includes a solenoid valve 8 for opening and closing to allow and stop a flow of a fuel gas supplied from a gas conduit 7, and a gas chamber 9 disposed in the air chamber 6 for receiving the fuel gas passing through the gas conduit 7.
The fuel gas supplied to the gas chamber 9 and the air fed to the air chamber 6 are flown into and sufficiently mixed with each other in a mixing chamber 10 arranged in the intake side of the combustion chamber 1. A mixture of the air and fuel gas is then supplied through a flame trap 11 to the combustion chamber 1, and ignited and explosively combusted in the combustion chamber 1. The negative pressure generated immediately after the explosion allows further admission of the fuel gas and the air into the mixing chamber 10 for subsequent combustion. Heat generated in such a cyclic explosion and combustion is applied to an object through the wail of the combustion chamber 1 and of the tail pipe 2.
The pulse combustor is further provided with an air flapper valve 12 and a gas flapper valve 13 respectively mounted at the inlets of the air and the fuel gas into the mixing chamber 10 to prevent back flow of combustion exhaust into the air supply system or the fuel gas supply system due to explosive combustion.
In the pulse combustor thus constructed, there is an undesirably large noise due to opening and closing of the air flapper valve 12 and the gas flapper valve 13, along with a combustion noise due to high combustion pressure. The conventional pulse combustor thus includes a silencer or an exhaust muffler 4 disposed in an exhaust conduit for noise reduction. The pulse combustor may also include an intake muffler (not shown) to prevent a noise from being generated at an intake of the fan 5.
It is known that mufflers generally used are divided into an expansion type and an resonance type, and in either type, a larger-sized muffler is required for effectively reducing a noise of a lower frequency. The pulse combustor thereby requires a relatively large muffler for effective noise reduction of pulse combustion at a low frequency (100 Hz in general). Such a large muffler prevents compact design of the pulse combustor, and moreover functions as a resistance to increase a pressure loss, which leads to a higher-power fan and enhanced fuel gas pressure.